The objectives of this research program are as follows: (1) Continue in vitro studies on the use of alloxan as a possible probe for the existence of glucoreceptors on the beta cell membrane, (2) Continue in vitro studies on the use of other triketones, similar in structure to alloxan, as possible probes for glucoreceptors on the beta cell membrane, (3) Continue studies on the mass isolation and subcellular fractionation of islets in order to obtain plasma membrane fractions for studies on glucose and alloxan binding as well as using secretory granules and membrane fractions for in vitro studies on emiocytosis, (4) Continue studies on the in vitro secretion of canine pancreatic polypeptide from the uncinate process of the dog pancreas and the in vitro secretion of human pancreatic polypeptide from isolated human islets.